This invention related to microwave circuits, and more particularly to RF interconnect techniques.
Known techniques for interconnecting MIC (Microwave Integrated Circuit) modules directly onto RF printed wiring boards (PWBs) includes coaxial cables or ribbons and connectors. The disadvantage to these techniques are size, weight, and cost. There are also reliability issues due to coefficient of thermal expansion (CTE) mismatches associated with the different packaging materials when direct solder and epoxy attach is used to mount these modules onto a PWB.
This invention offers a new, robust, serviceable and compact approach to microwave packaging. Separate and individual MIC modules can now be easily mounted and removed vertically, saving valuable real estate and height.
An RF interconnect is incorporated in RF module packages for direct attachment onto a multi-layer PWB using compressible center conductor (fuzz button) interconnects. The module has circuitry operating at microwave frequencies. The module package includes a metal housing including a metal bottom wall structure. The module includes a plurality of RF interconnects, which provide RF interconnection between the package and the PWB. Each interconnect includes a feedthrough center pin protruding through an opening formed in the metal bottom wall, with isolation provided by a dielectric feedthrough insulator. The center pin is surrounded with a ring of shield pins attached to the external surface of the bottom wall of the module housing. The pins are insertable in holes formed in the PWB, and make contact with fuzz button interconnects disposed in the holes. Circuitry connects the fuzz button interconnects to appropriate levels of the PWB for grounding and RF signal conduction.